Spring sash balance



1966 A. KAUFMAN ETAL 3,278,982

SPRING SASH BALANCE Filed Dec. 22, 1964 M f 6 12 W l Ilsa-var Kai/$3 235 4 tau/s KAUFMAN e 5 7. BY

ATTORNEY United States Patent 3,278,982 SPRING SASH BALANCE Albert Kaufman, 2111 Albemarle Road, Brooklyn, N.Y., Louis Kaufman, 110 N. Wood Lane, Woodmere,

Filed Dec. 22, 1964, Ser. No. 420,411 7 Claims. (Cl. 16197) This invention relates to a spring sash balance and more particularly to an improved torsion member therefor.

It is the object of the present invention to provide a rugged and sturdy torsion member, of low cost, for cooperation with a spring sash balance containing a coiled spiral spring within an axially rotating cylindrical element which is fabricated with a spiral rib on the exterior thereof. The torsion member is designed for easy assembly of few parts requiring no maintenance, and assuring smooth and effective operation over long periods of time.

It is another object of the invention to provide a torsion member comprising a guide loop for the cylindrical casing for the spiral spring, which loop is afiixed to the supporting bracket of the torsion member by means of a copper alloy stud, such as brass or bronze, provided with a slotted head disposed in the loop. The slot in the head engages the spiral rib on the cylindrical casing, which smoothly transforms the reciprocating movements of the window sash and casing into rotary movements of the latter without binding or jamming.

It is a further object of the invention to design the components of a spring sash balance to improve the operation thereof. More. particularly, the invention aimS to impose a differential control on the winding and un- Winding movements of the spiral spring in response to successive increments of movement of the window sash. This is attained by varying the pitch of the spiral rib on the cylindrical element which houses the spiral spring.

Other objects and purposes will appear from the detailed description of the invention following hereinafter, taken in conjunction with the accompanying drawings, wherein FIG. 1 is a vertical sectional view, with parts in elevation, showing the general arrangement of a spring sash balance seated within the edge of a window sash;

FIG. 2 is a front elevation of the torsion member in accordance with the invention;

FIG. 3 is a vertical sectional view along line 33 of FIG. 2;

FIG. 4 is a vertical sectional view along line 44 of FIG. 3; and

FIG. 5 is a horizontal sectional view along line 55 of FIG. 1.

The present invention is concerned with the improvement of window sash balances of the type disclosed in the US. patent to Forelich, No. 2,329,463, September 14, 1943.

As shown in the drawings, this type of spring sash balance is adapted to be seated within a groove G on each side of a window sash S and consists essentially of a cylindrical casing 1 formed of sheet metal and fabricated from a strip of sheeting which is joined at abutting edges to form a rib 2 extending spirally along the exterior surface of the tube 1. A spiral spring 3 within the tube 1 is afiixed at its lower end to stud 7 which extends upwardly from post 4, and to which is pivoted at the lower edge thereof a bracket plate 5 for aflixation to the bottom edge of the window sash through the intermediary of screw fastener 6. The upper end of the spiral spring 3 is secured for rotation with the tubular element 1 and the upper end of the tube 1 is additionally fitted with clutch spring 9 and adjusting screw 8 to adjust the tension of the spring 3, as fully disclosed in the above mentioned patent.

The cylindrical tube 1 may be constructed in many different ways and the spiral element 2 may assume the form of a slotted guide rather than a projecting rib as is well known in the art and as illustrated, for example, in US. Patent No. 2,260,056, October 21, 1941, as well as in U.S. Patent No. 2,329,463 mentioned above.

One of the essential improvements herein consists in the construction of the torsion member 10, which is adapted to be affixed to the window frame F by means of screw fastener 12 extending through opening 11 at the lower end of the bracket plate. A confining loop 13 for guiding the casing 1 is aflixed to the upper end of plate 10 through the intermediary of a brass or bronze stud 20 which is provided with a head 21 having a slot 22 in the face thereof. A shank 23, of smaller diameter than the head, is passed through an opening in the base of the loop as well 'as circular opening 17 in the upper end of the plate 10, and is swaged or peened over said opening at the rear face of plate 10 to securely interconnect the loop and bracket plate.

The confining loop 13 is formed from a piece of strip metal having the opposite edges 17, 18 thereof of complementary dove-tail configuration (FIG. 4), with lateral walls 14 and 15 extending perpendicularly from the base 17, 18 and With the semi-cylindrical arch 16 extending between the lateral walls 14 and 15. The loop 13 serves to embrace and guide the cylindrical tube 1 as the same is raised in the window frame. In addition, the diametral slot 22 of the stud 20 is set at an angle to the vertical corresponding to the pitch of the spiral rib 2, so that as the tube 1, with the external rib 2 thereon, moves relative to the loop 13, the slot 22 in the stud imparts rotary movement to the tube 1 and the spiral spring 3 seated therein.

The formation of the stud 20 of brass or bronze assures smooth operation of the spiral rib along the stud, without binding and jamming, and the stud furthermore assures a secure interconnection of the parts by the effective riveting action afforded by the peened surface 24 of the stud against the supporting plate 10. Thereby a smoothly operating spring sash balance is assured over long periods of time.

The metal from which the casing 1, the torsion member 10, and guide loop 13 are formed may be of low cost such as sheet steel, whereas the stud is formed of brass or bronze. Because of the small size of the stud this element of more expensive metal does not add substantially to the cost of the entire assembly. Nevertheless, the frictional action between the steel rib and slotted head of the brass or bronze stud results in a smoothly operating unit which is not attainable when the stud is formed of the same metal as the remainder of the torsion member.

The bracket portion of the torsion member 10 may extend downwardly relative to the stud 20, as shown in the drawing, or alternatively may extend upwardly there from. The former embodiment is used in conjunction with a spiral spring sash balance for a lower window frame, while the latter is used in conjunction with the upper window frame, as fully disclosed and illustrated in FIG. 1 of the above-mentioned Patent No. 2,329,463.

An improved control of the raising and lowering movements of the window sashes is attained by varying the pitch of the spiral rib along the length of the tubular element. Preferably the pitch of the spiral 2 is maintained uniform for about half of the length of the cylindrical tube 1 and thereafter the pitch decreases about one-half inch in the successive spirals. Thereby, for

example, the initial raising of the lower window sash for half of its distance, releases the energy stored up in the spring gradually and at the later increments of travel of the window sash the energy in the spring is released more rapidly per unit of movement of the sash. In the course of the reverse movement of the window, the released tension of the spring permits a more rapid winding thereof during the initial lowering 'movement of the window, and the winding movement is slowed up asthe window approaches its lower limit. Thereby the spring is subjected to minimum sudden stresses, which results in the long life thereof While assuring smooth lifting and lowering operations.

While we have described our invention as embodied in a specific form and as operating in a specific manner for purposes of illustration, it should be understood that we do not limit our invention thereto, since various modifications will suggest themselves to those skilled in the art without departing from the spirit of our invention, the scope of which is set forth in the annexed claims.

We claim:

1. A window sash balance comprising an axially rotating cylindrical element provided with a spiral spring in the interior thereof and a spiral rib on the exterior thereof, a torsion member adapted to be aflixed to a window frame to guide and to impart rotary movement to said element in response to reciprocating movements of the window sash, said torsion member comprising a supporting bracket plate having one end thereof aflixed to the window frame and provided with a circular opening at the opposite end thereof, a sheet metal confining loop embracing said cylindrical element, means for affixing said loop to said plate at said opening comprising a copper alloy stud having a slotted head within said loop and a shank of smaller diameter than said head projecting therefrom and peened over said bracket plate on the face thereof remote from said loop, with the slot in the head disposed at an inclination to the vertical corresponding to the pitch of said rib for permanent engagement with said rib as the cylindrical element is;

moved relative thereto, whereby rotary movement is imparted to said element.

2. A device as set forth in claim 1 wherein said loop is formed of a flat Fblank of low-cost sheet metal having a fiat face in abutting contact with said supporting bracket plate, a wall extending perpendicularly from each side.

of said face and merging in ,a semi-cylindrical arch .remotely from said face.

3. A device as set forth in claim 2 wherein said flat face of the loop is formed of the opposite portions of the flat blank of sheet metal, the edges of which are dovetailed into each other, with the head of the stud 'ove rlying relation thereto.

4. A device as set forth in claim.2 wherein the loop is formed of steel and the stud is formed of brass.

; 5. A device. as set forth in claim 1 wherein said .cylindrical element and rib are formed of steel and said stud is formed of brass.

6. A device as set forth in claim 1 wherein the spiral rib on the exterior of the cylindrical element is of varying pitch to vary the torsion forces imposed on said spiral spring at different increments of movement of the window sash.

" 7. A device as set forth in claim 6 wherein the pitch of the spiral rib is substantially uniform along the first half of the cylindrical element and decreases progressively along the other half thereof.

EDWARD C. ALLEN, Primary Examiner. I. H. MCVGLYNN, Assistant Examiner. 

1. A WINDOW SASH BALANCE COMPRISING AN AXIALLY ROTATING CYLINDRICAL ELEMENT PROVIDED WITH A SPIRAL SPRING IN THE INTERIOR THEREOF AND A SPIRAL RIB ON THE EXTERIOR THEREOF, A TORSION MEMBER ADAPTED TO BE AFFIXED TO A WINDOW FRAME TO GUIDE AND TO IMPART ROTARY MOVEMENT TO SAID ELEMENT IN RESPONSE TO RECIPROCATING MOVEMENTS OF THE WINDOW SASH, SAID TORSION MEMBER COMPRISING A SUPPORTING BRACKET PLATE HAVING ONE END THEREOF AFFIXED TO THE WINDOW FRAME AND PROVIDED WITH A CIRCULAR OPENING AT THE OPPOSITE END THEREOF, A SHEET METAL CONFINING LOOP EMBRACING SAID CYLINDRICAL ELEMENT, MEANS FOR AFFIXING SAID LOOP TO SAID PLATE AT SAID OPENING COMPRISING A COPPER ALLOY STUD HAVING A SLOTTED HEAD WITHIN SAID LOOP AND A SHANK OF SMALLER DIAMETER THAN SAID HEAD PROJECTING THEREFROM AND PEENED OVER SAID BRACKET PLATE ON THE FACE THEREOF REMOTE FROM SAID LOOP, WITH THE SLOT IN THE HEAD DISPOSED AT AN INCLINATION TO THE VERTICAL CORRESPONDING TO THE PITCH OF SAID RIB FOR PERMANENT ENGAGEMENT WITH SAID RIB AS THE CYLINDRICAL ELEMENT IS MOVED RELATIVE THERETO, WHEREBY ROTARY MOVEMENT IS IMPARTED TO SAID ELEMENT. 